org.neo4j.commandline.dbms.StoreLockChecker Maven / Gradle / Ivy

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This component provides management functionality and product surface for Neo4j instances.
There is a newer version: 5.23.0
/*
 * Copyright (c) 2002-2020 "Neo4j,"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package org.neo4j.commandline.dbms;

import java.io.Closeable;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;

import org.neo4j.io.IOUtils;
import org.neo4j.io.fs.DefaultFileSystemAbstraction;
import org.neo4j.io.fs.FileSystemAbstraction;
import org.neo4j.io.layout.StoreLayout;
import org.neo4j.kernel.StoreLockException;
import org.neo4j.kernel.internal.locker.GlobalStoreLocker;
import org.neo4j.kernel.internal.locker.StoreLocker;

class StoreLockChecker implements Closeable
{

    private final FileSystemAbstraction fileSystem;
    private final StoreLocker storeLocker;

    private StoreLockChecker( FileSystemAbstraction fileSystem, StoreLayout storeLayout )
    {
        this.fileSystem = fileSystem;
        this.storeLocker = new GlobalStoreLocker( fileSystem, storeLayout );
    }

    /**
     * Create store lock checker with lock on a provided store layout if it exists and writable
     * @param storeLayout store layout to check
     * @return lock checker or empty closeable in case if path does not exists or is not writable
     * @throws CannotWriteException
     *
     * @see StoreLocker
     * @see Files
     */
    static Closeable check( StoreLayout storeLayout ) throws CannotWriteException
    {
        Path lockFile = storeLayout.storeLockFile().toPath();
        if ( Files.exists( lockFile ) )
        {
            if ( Files.isWritable( lockFile ) )
            {
                StoreLockChecker storeLocker = new StoreLockChecker( new DefaultFileSystemAbstraction(), storeLayout );
                try
                {
                    storeLocker.checkLock();
                    return storeLocker;
                }
                catch ( StoreLockException le )
                {
                    try
                    {
                        storeLocker.close();
                    }
                    catch ( IOException e )
                    {
                        le.addSuppressed( e );
                    }
                    throw le;
                }
            }
            else
            {
                throw new CannotWriteException( lockFile );
            }
        }
        return () ->
        {
        };
    }

    private void checkLock()
    {
        storeLocker.checkLock();
    }

    @Override
    public void close() throws IOException
    {
        IOUtils.closeAll( storeLocker, fileSystem );
    }
}